POWER-OVER-ETHERNET (PoE) CONTROL SYSTEM

ABSTRACT

One example includes a power-over-Ethernet (PoE) control system. The system includes a powered device (PD) that is configured to receive a voltage signal via an Ethernet connection and which comprises a PoE signal receiver configured to indicate a nominal power level via the received voltage signal. The system also includes a power sourcing equipment (PSE) device configured to generate the voltage signal and to measure a class current of the voltage signal to determine the nominal power level. The PSE device includes a PoE controller configured to provide a power setting command as a function of the nominal power level to the PoE signal receiver via the voltage signal, such that the PD can operate at a power level that is based on the power setting command.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Nonprovisional applicationSer. No. 14/448,753, filed Jul. 31, 2014, which claims the benefit ofU.S. Provisional Patent Application No. 61/864,179, filed Aug. 9, 2013,and entitled PoE LIGHTING CLASSIFICATION AND CONTROL METHOD, FOUR PAIRSHIGH POWER, which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

This disclosure relates generally to electronic systems, and morespecifically to a power-over-Ethernet (PoE) control system.

BACKGROUND

A variety of control systems can be implemented to provide power andcontrol to power consuming equipment, such as lighting devices or othertypes of devices that consume power. One such control system isPower-over-Ethernet (PoE), such as defined by the IEEE 802.3at standard,is a manner of safely providing power to a powered device (PD) over acable via power sourcing equipment (PSE), and of removing power if a PDis disconnected. As an example, the process proceeds through an idlestate and three operational slates of detection, classification, andoperation. During detection, the PSE can leave the cable unpowered inthe idle state while it periodically looks to see if a PD has beenplugged-in. The low-power levels that can be used during detection areunlikely to damage devices not designed for PoE. If a valid PD signatureis present, during classification, the PSE may inquire as to how muchpower the PD requires. The PSE may then provide the required power tothe PD if it has sufficient power providing capacity.

SUMMARY

One example includes a power-over-Ethernet (PoE) control system. Thesystem includes a powered device (PD) that is configured to receive avoltage signal via an Ethernet connection and which comprises a PoEsignal receiver configured to indicate a nominal power level via thereceived voltage signal. The system also includes a power sourcingequipment (PSE) device configured to generate the voltage signal and tomeasure a class current of the voltage signal to determine the nominalpower level. The PSE device includes a PoE controller configured toprovide a power setting command as a function of the nominal power levelto the PoE signal receiver via the voltage signal, such that the PD canoperate at a power level that is based on the power setting command.

Another example includes a method for providing power control in a PoEcontrol system. The method includes providing event classifications of avoltage signal via an Ethernet connection from a PSE device. The methodalso includes indicating a nominal power level based on a classsignature via a PoE signal receiver of a powered device (PD) based on aclass current of the voltage signal. The method also includes providinga power setting command associated with a quantity of class events ofthe voltage signal from the PSE device to the PoE signal receiver. Thepower setting command can correspond to a percentage of the nominalpower level. The method further includes activating the PD to operate atthe percentage of the nominal power level based on the power settingcommand.

Another example includes a PoE control system. The system includes apowered device (PD) that is configured to receive a voltage signal viaan Ethernet connection and which comprises a PoE signal receiverconfigured to provide a first class signature in response to a firstevent classification via a class current of the received voltage signaland a second class signature via the class current, the second classsignature having a different class value from the first class signature,and a third class signature that has a class value that is less than thesecond class signature to indicate that the PD has a capacity for PoEcontrol. The third class signature can indicate a nominal power level ofthe PD. The system further includes a PSE device configured to generatethe voltage signal and to measure the class current of the voltagesignal to determine the capacity for PoE control and the nominal powerlevel. The PSE device includes a PoE controller configured to provide apower selling command as a function of the nominal power level to thePoE signal receiver via the voltage signal, such that the PD can operateat a power level that is based on the power setting command.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a power-over-Ethernet (PoE) controlsystem.

FIG. 2 illustrates another example of a PoE control system.

FIG. 3 illustrates an example of a timing diagram.

FIG. 4 illustrates yet another example of a PoE control system.

FIG. 5 illustrates another example of a timing diagram.

FIG. 6 illustrates an example of a method for providing power control ina PoE control system.

DETAILED DESCRIPTION

This disclosure relates generally to electronic systems, and morespecifically to a power-over-Ethernet (PoE) control system. A PoEcontrol system can include a power sourcing equipment (PSE) device and apowered device (PD) that are electrically coupled via an Ethernetconnection, such as an RJ-45 cable. As an example, the PD can correspondto a lighting system or any of a variety of other electronic devicesthat consume a varying amount of power. The PSE device includes a PoEcontroller and is configured to provide a voltage signal that can varyin amplitude depending on the phase of PoE control. The PD can include aPoE signal receiver that is configured as a current source in responseto the voltage signal provided by the PSE device. The PoE controller canmonitor the class current of the voltage signal to determine classsignatures. In this manner, the PD can include a PoE signal receiver toindicate to the PSE device that the PD has a capacity for PoE control,and can indicate a nominal power level of the PD to the PSE device viathe class current of the voltage signal. Therefore, the PSE device canprovide pulses via the voltage signal as a power setting command to thePD, such that the PD can operate at a power level that is based on thepower setting command.

For example, subsequent to a detection phase during which the PSE devicedetermines if the PD is connected, the PSE device can operate in aclassification phase. During the classification phase, the PSE devicecan provide the voltage signal at a classification amplitude to provideevent classifications that include one or more class events andcorresponding mark events (e.g., in a 1-Event or 2-Event classificationscheme) via the voltage signal to the PD, such that the PD can controlthe class current of the voltage signal to provide respective classsignatures to the PSE device. As an example, the PD can provide a firstclass signature and a second class signature, with the first and secondclass signatures being different. Subsequent to the second classsignature, the PD can provide a third class signature to the PSE devicethat is less than the second class signature to indicate the capacityfor PoE control by the PSE device. As another example, the third classsignature can indicate a nominal power level of the PD to the PSEdevice. For example, the third class signature can have a valuecorresponding to one of a plurality of predetermined nominal powerlevels, such that the PSE device can identify the nominal power levelbased on the value of the third class signature.

Subsequent to the indication of the nominal power levels the PSE devicecan provide a number of class events that can correspond to a codecorresponding to the power setting command, with the quantity of pulsescorresponding a predetermined percentage of the nominal power level. Asa result, the PSE device can provide the voltage signal in theactivation phase at a maximum amplitude, such that the PD can operate atthe percentage of the nominal power level based on the power commandsetting. Accordingly, the PoE control system described herein canoperate to provide physical (PHY) layer power control of the PD in asimplistic and variable manner.

FIG. 1 illustrates an example of a power-over-Ethernet (PoE) controlsystem 10. The PoE control system 10 can be implemented in a variety ofpower-providing applications, such as illumination. For example, the PoEcontrol system 10 can be implemented to provide power control viaexisting Ethernet cables (e.g., RJ-45 cables) without Ethernet datacommunication capability (e.g., utilizing data/link layers,packetization, etc.). Accordingly, as described herein, the PoE controlsystem 10 provides PoE power control in a physical (PHY) layer manner.

The PoE control system 10 includes a power sourcing equipment (PSE)device 12 and a powered device (PD) 14 that are electrically coupledvis. an Ethernet connection 16. As an example, the Ethernet connection16 can be an RJ-45 cable that implements twisted pair conductors (e.g.,four twisted pairs). The PSE device 12 is configured to provide avoltage signal V_(PORT) to the powered device via the Ethernetconnection 16 to implement bilateral communication between the PSEdevice 12 and the PD 14. For example, the voltage V_(PORT) cancorrespond to a feed voltage V_(POE) that is generated in the PSE device12 and which is modulated in amplitude. As an example, the PD 14 can beconfigured as a Type 2 PD according to the IEEE 802.3 standard.

As described herein, the voltage signal V_(PORT) can correspond to avoltage signal that varies to provide event classifications from the PSEdevice 12 to the PD 14 in an event classification scheme, such that thePD 14 can respond to the class events by varying the current of thevoltage signal V_(PORT) to provide a class signature to the PSE device12, such as based on the IEEE 802.3 standard. As also described herein,the term “event classification” describes the PSE device 12 providingone or more class events and corresponding mark events to the PD 14 toprovide communication to and/or to elicit a communication response fromthe PD 14 in the form of a class signature. As also described herein,the term “class event” describes a pulse of the voltage signal V_(PORT)at a predetermined amplitude, and which is followed by a mark event(e.g., decreased voltage subsequent to the pulse) that signifies an endof the class event. As further described herein, the term “classsignature” refers to a response by the PD 14 of an event classificationthat includes the one or more class events in the form of a magnitude ofclass current that corresponds to a class level, described herein asClass 0 through Class 5, with the class values corresponding toincreasing amplitudes of the class current in ascending order of classvalue.

In the example of FIG. 1, the PSE device 12 includes a PoE controller18, and the PD 14 includes a PoE signal receiver 20. The PoE controller18 can be configured to control an activation time and an amplitude ofthe voltage signal V_(PORT), such as based on a given operating phase ofthe PoE control system 10, to provide communication to the PD 14. ThePoE controller 18 can also be configured to measure the class currentassociated with the voltage signal V_(PORT), and thus to determine theclass level of a class signature. The PoE signal receiver 20 can beconfigured to receive the voltage signal V_(PORT) and to act as a classcurrent source with respect to the voltage signal V_(PORT) such that thePoE signal receiver 20 can adjust the class current of the voltagesignal V_(PORT) to provide communication to the PSE device 12 inresponse to the voltage signal V_(PORT). As an example, the PoEcontroller 18 can implement the communication with the PoE signalreceiver 20 via a standard, such as IEEE 802.3. For example, the PoEcontroller 18 can be configured to provide event classifications as a1-Event Physical Layer classification to provide a single class event,or as a 2-Event Physical Layer classification to provide a series (e.g.,two) of class events followed by respective mark events. In response,the PD 14 can provide a corresponding class signature. As describedherein, the term

As an example, the PSE device 12 can initially operate in a detectionphase, such that the PSE device 12 can provide the voltage signalV_(PORT) at a valid test voltage amplitude (e.g., between approximately2.8 volts and approximately 10 volts) at periodic intervals. If the PD14 Is electrically coupled to the PSE device 12 via the Ethernetconnection 16, the PoE signal receiver 20 can respond by providing asufficient resistance with respect to the voltage signal V_(PORT) toindicate to the PSE device 12 that the PD 14 is coupled via the Ethernetconnection 16. Subsequent to the detection phase, the PSE device 12switches to a classification phase.

During the classification phase, the PSE device 12 can provide thevoltage signal V_(PORT) at a classification amplitude (e.g., betweenapproximately 15.5 volts and approximately 20.5 volts) to provide classevents (e.g., 1-Event classifications and/or 2-Event classifications)via the voltage signal V_(PORT) to the PD 14, as controlled by the PoEcontroller 18. In response to the class events, the PoE signal receiver20 can control the class current of the voltage signal V_(PORT) toprovide respective class signature to the PSE device 12, such that eachclass signature has a range of class current amplitudes that correspondsto a predetermined Class (e.g., as dictated by IEEE 802.3at). Asdescribed previously, the PoE controller 18 can measure the classcurrent of the voltage signal V_(PORT) in each class event, such thatthe PoE controller 18 can determine the class signature provided by thePoE signal receiver 20. Accordingly, as described herein, the PSE device12 and the PD 14 can communicate with each other.

As an example in the classification phase, the PoE signal receiver 20can provide a first class signature in response to a first eventclassification, followed by a second class signature in response to asecond event classification, and a third class signature in response toa third event classification. The PoE signal receiver 20 can provide thesecond class signature at a different class (e.g., at a greater current)than the first class signature, and can provide the third classsignature at a class less than the second class signature to indicatethe capacity for PoE control of the PD 14 by the PSE device 12. Forexample, the first class signature can be provided at Class 4 (e.g., inresponse to each of two class events of the first event classification),the second class signature can be provided at Class 5, and the thirdclass signature can be provided at a range of classes less than Class 5(e.g., Class 0-4). As described herein, the term “Class 5” with respectto a class signature is defined as a class signature having a higherclass current than a Class 4 class signature, such as implemented In theIEEE 802.3 standard. Therefore, in response to the values in thesequence of the classes provided by the PoE signal receiver 20, the PoEcontroller 18 can identify that the PD 14 has a capacity for PoE controlby the PSE device 12.

In response to a determination of the capacity for PoE control of the PD14 by the PSE device 12, the PD 14 can provide an indication of anominal power level of the PD 14 to the PSE device 12. As describedherein, the nominal power level of the PD 14 corresponds to a maximumpower consumption of the PD 14 at full and normal operating conditions(e.g., full light level for a PoE lighting system). For example, thethird class signature that is less than the second class signature canhave a class value (e.g., one of Class 0-4) corresponding to one of aplurality of predetermined nominal power levels, such that the PoEcontroller 18 can identify the nominal power level based on the value ofthe third class signature. In response to identifying the nominal powerlevel of the PD 14, the PoE controller 18 can be configured to controlthe power level of the PD 14 as a function of the nominal power level,such that the power output of the PD 14 can be variably controlled bythe PoE controller 18.

For example, subsequent to the indication of the nominal power level,the PoE controller 18 can provide a number of class events via thevoltage signal V_(PORT) associated with a code corresponding to thepower setting command. As an example, the power setting command can beencoded based on a quantity of pulses of the class events correspondingto a predetermined percentage of the nominal power level. In response tothe code, the PoE signal receiver 20 can identify the portion (e.g.,percentage) of the nominal power level that is desired to be output fromthe PD 14 by the PoE controller 18. As a result, the PSE device 12 canprovide the voltage signal V_(PORT) in the activation phase at a maximumpower on amplitude (e.g., between approximately 44 volts andapproximately 57 volts, as dictated by a maximum voltage of anassociated power supply). Therefore, the PD 14 can operate at thepercentage of the nominal power level based on tire power commandsetting. Accordingly, the PoE control system 10 described herein canoperate to provide PHY layer power control of the PD 14 in a simplisticand variable manner.

FIG. 2 illustrates another example of a PoE control system 50. The PoEcontrol system 50 can correspond to the PoE control system 10 in theexample of FIG. 1, such as in a PoE lighting application. For example,the PoE control system 50 can be implemented to provide power controlvia existing Ethernet cables (e.g., RJ-45 cables) without Ethernet datacommunication capability (e.g., utilizing data/link layers,packetization, etc.).

The PoE control system 50 includes a PSE device 52 and a PD 54 that areelectrically coupled via an Ethernet connection 56. In the example ofFIG. 2, the Ethernet connection 56 is demonstrated as an RJ-45 cablethat implements four twisted pair conductors. Therefore, the Ethernetconnection 56 is demonstrated in the example of FIG. 2 as including twocommunication ports, demonstrated as PORT 1. and PORT 2. The PSE device52 Includes a voltage source 58 that is configured to generate a voltagesignal V_(POE). In the example of FIG. 2, the PSE device 52 includes aPoE controller 60 that provides a voltage control signal P_CTL to thevoltage source 58 to control the amplitude of the voltage signal V_(POE)(e.g., depending on the operating phase), and to measure the classcurrent of the voltage signal V_(POE). The PoE controller 60 is alsoconfigured to generate a switching signal SW to control a set ofswitches S₁ and S₂ to provide the voltage signal V_(POE) and alow-voltage (e.g., ground) connection, respectively, to the PD 54 viathe Ethernet connection 56 as the voltage V_(PORT) in the example ofFIG. 1. Therefore, In response to the switching signal SW, the voltagesignal V_(PORT) is provided to the PD 54 based on the voltage V_(POE)via each of PORT 1 and PORT 2. Accordingly, the PoE controller 60 can beconfigured to control an activation time and an amplitude of the voltagesignal V_(PORT), such as based on a given operating phase of the PoEcontrol system 50, to provide communication to the PD 54. As oneexample, the voltage signal V_(POE) can be provided via the voltagesource 58 as the variable voltage V_(PORT). As another example, thevoltage signal V_(POE) can be constant (e.g., between approximately 44volts and approximately 57 volts), and the PSE device 52 can beconfigured to modulate the impedance of the switch S₁ to provide thevariable voltage V_(PORT) provided to the PD 54.

In the example of FIG. 2, the PD 54 includes a pair of rectifiers 62that are each coupled to the Ethernet connection 56 at the respectiveports PORT 1 and PORT 2. The rectifiers 62 are configured to provide thevoltage signal V_(PORT) across a capacitor C_(PD). In the example ofFIG. 2, the PD 54 includes a PoE signal receiver 64 (“PoE RX”) thatreceives a voltage V_(P) corresponding to the voltage signal V_(PORT)across the capacitor C_(PD). The PoE signal receiver 64 thus receivesthe voltage V_(P)and acts as a current source with respect to thevoltage V_(P), and thus the voltage signal V_(PORT), such that the PoEsignal receiver 64 can adjust the class current of the voltage signalV_(PORT) to provide communication to the PSE device 52 in response tothe voltage signal V_(PORT). In addition, the PD 54 includes a powercontroller 66 to which the PoE signal receiver 64 can provide a controlsignal CTRL. Therefore, in response to a power setting command providedto the PoE signal receiver 64 by the PoE controller 60, the PoE signalreceiver 64 can indicate a desired output power level, such as being afunction (e.g., percentage) of the nominal power level of the PD 54, tothe power controller 66 via the control signal CTRL. Accordingly, duringthe activation phase described in greater detail herein, the powercontroller 66 can provide the desired output power dictated by the powersetting command in response to the full amplitude of the voltage signalV_(PORT) provided by the PSE device 52.

FIG. 3 illustrates an example of a timing diagram 100. The timingdiagram 100 demonstrates an amplitude of the voltage signal V_(P) as afunction of time. The timing diagram 100 can correspond to operation ofthe PoE control system 50. Therefore, reference is to be made to theexample of FIG. 2 in the following description of the example of FIG. 3.

Prior to a time T₀, the voltage signal V_(P) can have an amplitudeV_(MIN), corresponding to a substantially minimum voltage (e.g., zerovolts). As an example, the amplitude V_(MIN) could correspond to anactual voltage amplitude of the voltage signal V_(P), or couldcorrespond to the switches S₁ and S₂ being open. At the time T₀, the PSEdevice 52 can begin operating in a detection phase, such that thevoltage signal V_(P) increases to a low amplitude V_(VALID1) betweenapproximately 2.8 volts and approximately 10 volts). Since the PD 54 iselectrically coupled to the PSE device 52 via the Ethernet connection56, the PoE signal receiver 64 can respond by providing a sufficientresistance with respect to the voltage signal V_(P) to indicate to thePSE device 52 that the PD 54 is coupled via the Ethernet connection 56.At a time T₁, the voltage signal V_(P) decreases to an amplitudeV_(VALID2) (e.g., also between approximately 2.8 volts and approximately10 volts, but different (e.g., less) than the amplitude V_(VALID1)).Therefore, the PSE device 52 can determine the resistance value of thePoE signal receiver 64 based on a ΔI/ΔV of the separate amplitudesV_(VALID1) and V_(VALID2). At a time T₂, the amplitude V_(MIN), thusconcluding the detection phase. While the detection phase isdemonstrated in the example of FIG. 3 as including only a singledifferential measurement of the voltage signal V_(P) at the amplitudesV_(VALID1) and V_(VALID2), it is to be understood that the detectionphase could include differential measurements and/or additionalamplitudes in the detection phase voltage amplitude range, such asdictated by the IEEE 802.3at standard.

At the time T₃, the PSE device 52 switches to a classification phase,during which the PoE controller 60 can determine whether the PD 54 has acapacity for PoE control, can determine a nominal power level of the PD54, and can provide a power setting command to the PoE signal receiver64. Beginning at the time T₃, the PSE device 52 provides a first eventclassification, demonstrated at 102 as a 2-Event classification. At thetime T₃, the voltage signal V_(P) is provided at an amplitude V_(CLASS)in a first class event. The amplitude V_(CLASS) can correspond to avoltage amplitude in a classification amplitude range amplitude (e.g.,between approximately 15.5 volts and approximately 20.5 volts). Inresponse to receiving the voltage signal V_(P) of the first class eventat the time T₃ (e.g., via the voltage V_(P)), the PoE signal receiver 64can indicate a first class value (e.g., Class 4). At a time T₄, thevoltage signal V_(P) can decrease to an amplitude V_(MRK), correspondingto a mark event. As an example, the mark event can signify to the PoEsignal receiver 64 the end of the first class event. Similarly, at atime T₅, the PSE device 52 provides the voltage signal V_(P) at theamplitude V_(CLASS) in a second class event of the first eventclassification (e.g., of the 2 Event classification), in response towhich the PoE signal receiver 64 can provide a second class value (e.g.,Class 4), followed by another mark event at a time T₆. As an example,the first and second class values can be equal (e.g., Class 4). Thus,the PD 14 can respond to the first event classification with a classsignature that comprises two Class 4 current responses to the respectivetwo class events of the first event classification 102. The example ofFIG. 3 demonstrates that the first event classification 102 comprisestwo class events in a 2-Event classification scheme, such as to ensure alinear response to a substantially constant amplitude of the voltagesignal V_(P)at the classification amplitude range. However, it is to beunderstood that the PoE controller 60 can be configured to provide thefirst event classification as a 1-Event classification by providing asingle class event, or based on providing more than two class events.

At a time T₇, the PSE device 52 again provides the voltage signal V_(P)at an amplitude V_(CLASS) in a second event classification (e.g., a1-Event classification), demonstrated at 104. In response to receivingthe voltage signal V_(P) in a class event of the second eventclassification 104 (e.g., via the voltage V_(P)), the PoE signalreceiver 64 can provide a second class signature (e.g., Class 5). At atime T₈, the voltage signal V_(P) cart decrease to the amplitudeV_(MRK), corresponding to a mark event of the second eventclassification 104, thus signifying to the PoE signal receiver 64 theend of the class event of the second event classification 104. Thesecond class signature can be provided by the PoE signal receiver 64 ata value that is different from (e.g., greater than) the first classsignature, thus potentially signifying to the PoE controller 60 that thePD 54 may have a capacity for PoE control.

At a time T₉, the PSE device 52 again provides the voltage signal V_(P)at an amplitude V_(CLASS) & third event classification, demonstrated at106. In response to receiving the voltage signal V_(P) in the thirdevent classification 106 (e.g., via the voltage V_(P)), the PoE signalreceiver 64 can provide a third class signature at a value that is lessthan the second class signature (e.g., Class 0-4). At a time T₁₀, thevoltage signal V_(P) can decrease to the amplitude V_(MRK),corresponding to a mark event, thus signifying to the PoE signalreceiver 64 the end of the third event classification 106. The thirdclass signature can be provided by the PoE signal receiver 64 at a valuethat is less than the second class signature to indicate to the PoEcontroller 60 that the PD 54 has a capacity for PoE control. Inaddition, the specific class value of the third class signature 106 canindicate to the PoE controller 60 the nominal power level of the PD 54.For example, the class value of the third class signature can correspondto one of a plurality of predetermined nominal power levels, such thatthe PoE controller 60 can identify the nominal power level based on thevalue of the third class signature, such as provided in Table 1 below:

TABLE 1 Third Class Nominal Power Signature Value Level of the PD 54 015 W 1 30 W 2 45 W 3 60 W 4 90 WThe predetermined nominal power levels demonstrated in the example ofTable 1 are provided only by example, in that any of a variety of otherpredetermined nominal power levels can be provided in the communicationfrom the PoE signal receiver 64 to the PoE controller 60 via the thirdclass signature.

As described previously, in response to identifying the nominal powerlevel of the PD 54, the PoE controller 60 can be configured to controlthe power level of the PD 54 as a function of the nominal power level,such that the power output of the PD 54 can be variably controlled bythe PoE controller 60. At a time T₁₁, the PoE controller 60 can begin toprovide a number of event classifications (e.g., 1-Eventclassifications) via the voltage signal V_(P) associated with a codecorresponding to the power setting command. As an example, the powersetting command can be encoded based on a quantity of class eventscorresponding to a predetermined percentage of the nominal power level,such as provided in Table 2 below:

Quantity of Class Percentage of Events Nominal Power Level 0 100%  1 80%2 55% 3 30%

The predetermined percentage values of the nominal power leveldemonstrated in the example of Table 2 are provided only by example, inthat the PoE controller 60 can be configured to provide any of a varietyof predetermined quantities corresponding to associated percentages ofnominal power level. The example of FIG. 3 demonstrates a single classevent with associated mark event subsequently at the time T₁₁. However,it is to be understood that the PoE controller 60 can be configured toprovide zero class events to signify a desired power level of the PD 54.

In response to the code, the PoE signal receiver 64 can identify thepercentage of the nominal power level that is desired to be output fromthe PD 54 by the PoE controller 60. As a result, at a time T₁₂, the PSEdevice 52 begins operating in the activation phase, and thus providesthe voltage signal V_(P) at a maximum amplitude V_(PORT) _(_) _(PSE)(e.g., between approximately 44 volts and approximately 57 volts, asdictated by a maximum voltage of an associated power supply). Therefore,the PD 54 can operate at the percentage of the nominal power level basedon the power command setting. Accordingly, the PoE control system 50described herein can operate to provide PHY layer power control of thePD 54 in a simplistic and variable manner.

FIG. 4 illustrates yet another example of a PoE control system 150. ThePoE control system 150 can correspond to the PoE control system 10 Inthe example of FIG. 1, such as in a PoE lighting application. Forexample, the PoE control system 150 can be implemented to provide powercontrol via existing Ethernet cables (e.g., RJ-45 cables) withoutEthernet data communication capability (e.g., utilising data/linklayers, packetization, etc.).

The PoE control system 150 includes a PSE device 152 and a PD 154 thatare electrically coupled via an Ethernet connection 156. In the exampleof FIG. 4, the Ethernet connection 156 is demonstrated as an RJ-45 cablethat implements four twisted pair conductors. Therefore, the Ethernetconnection 156 is demonstrated in the example of FIG. 4 as including twocommunication ports, demonstrated as PORT 1 and PORT 2. The PSE device152 includes a voltage source 158 that is configured to generate avariable voltage signal V_(POE). Similar to as described previously inthe example of FIG. 3, the PSE device 152 can provide the voltageV_(POE) in a variable manner as the voltage V_(PORT) across the Ethernetconnection 156.

In the example of FIG. 4, the PSE device 152 includes a PoE controller160 that provides a voltage control signal P_CTL to the voltage source158 to control the amplitude of the voltage signal V_(POE) (e.g.,depending on the operating phase), and to measure the class current ofthe voltage signal V_(PORT). The PoE controller 160 is also configuredto generate a pair of switching signals SW₁ and SW₂ to control arespective set of switches S₁ and S₂ to provide the voltage signalV_(POE) and a low-voltage (e.g., ground) connection, respectively, tothe FD 154 via the Ethernet connection 156. Therefore, in response tothe switching signal SW₁, the voltage signal V_(PORT) is provided to thePD 154 via PORT 1, and in response to the switching signal SW₂, thevoltage signal V_(PORT) ts provided to the PD 154 via PORT 2.Accordingly, the PoE controller 160 can be configured to control anactivation time and an amplitude of the voltage signal V_(PORT) on eachof PORTS 1 and 2 individually, such as based on a given operating phaseof the PoE control system 150, to provide communication to the PD 154.

In the example of FIG. 4, the PD 154 includes a first rectifier 162 thatis coupled to the Ethernet connection 156 at PORT 1 and a secondrectifier 163 that Is coupled to the Ethernet connection 156 at PORT 2.The first rectifier 162 is configured to provide the voltage signalV_(PORT) across a first capacitor C_(PD1) and the second rectifier 163is configured to provide the voltage signal V_(PORT) across a secondcapacitor C_(PD2). In the example of FIG. 4, the PD 154 includes a firstPoE signal receiver 164 (“PoE RX1”) that receives a voltage V_(P1)corresponding to the voltage signal V_(PORT) across the first capacitorC_(PD1) and a second PoE signal receiver 165 (“PoE RX2”) that receives avoltage V_(P2) corresponding to the voltage signal V_(PORT) across thesecond capacitor C_(PD2).

The first PoE signal receiver 164 thus receives the voltage VPD1 andacts as a current source with respect to the voltage VPD1, and thus thevoltage signal V_(PORT), such that the first PoE signal receiver 164 canadjust the class current of the voltage signal V_(PORT) to providecommunication to the PSE device 152 in response to the voltage signalV_(PORT). Similarly, the second PoE signal receiver 165 thus receivesthe voltage VPD2 and acts as a current source with respect to thevoltage VPD2, and thus the voltage signal V_(PORT), such that the secondPoE signal receiver 164 can adjust the class current of the voltagesignal V_(PORT) to provide communication to the PSE device 152 Inresponse to the voltage signal V_(PORT). In addition, the PD 154includes a power controller 166 to which the first and second PoE signalreceivers 164 and 165 can provide respective control signals CTRL1 andCTRL2. Therefore, In response to a power setting command provided to atleast one of the PoE signal receivers 164 and 165 by the PoE controller160, the PoE signal receiver(s) 164 and 165 can indicate a desiredoutput power level, such as being a function (e.g., percentage) of thenominal power level of the PD 154, to the power controller 166 via thecontrol signal(s) CTRL1 and CTRL2. Accordingly, during the activationphase described in greater detail herein, the power controller 166 canprovide the desired output power dictated by the power setting commandin response to the full amplitude of the voltage signal V_(PORT)provided by the PSE device 152.

FIG. 5 illustrates an example of timing diagrams 200 and 201. The timingdiagram 200 demonstrates an amplitude of the voltage V_(P1) as afunction of time, and the timing diagram 201 demonstrates an amplitudeof the voltage V_(P2) as a function of time. The timing diagrams 200 and201 can correspond to operation of the PoE control system 150.Therefore, reference is to be made to the example of FIG. 4 in thefollowing description of the example of FIG. 5. Thus, the voltage V_(P1)corresponds to the voltage V_(PORT) in response to activation of theswitch S₁ via the switching signal SW₁, and voltage V_(P2) correspondsto the voltage V_(PORT) in response to activation of the switch S₂ viathe switching signal SW₂.

Prior to a time T₀, the voltages V_(P1) and V_(P2) can each have anamplitude V_(MIN), corresponding to a substantially minimum voltage(e.g., zero volts). As an example, the amplitude V_(MIN) couldcorrespond to an actual voltage amplitude of the voltages V_(P1) andV_(P2), or could correspond to the switches S₁ and S₂ being open. At thetime T₀, the PSE device 152 can begin operating in a detection phase,such that the voltage V_(P1) increases to the amplitude V_(VALID1).Since the PD 154 is electrically coupled to the PSE device 152 via theEthernet connection 156, the first PoE signal receiver 164 can respondby providing a sufficient resistance with respect to the voltage V_(P1)to indicate to the PSE device 132 that the PD 154 is coupled via theEthernet connection 156. At a time T₁, the voltage V_(P1) decreases toan amplitude V_(VALID1), while the voltage V_(P2) increases to theamplitude V_(VALID1). At a time T₂, the voltage V_(P1) decreases back tothe amplitude V_(MIN). Similarly, at a time T₂, the voltage V_(P2)decreases to the amplitude V_(VALID2). Since the PD 154 is electricallycoupled to the PSE device 152 via the Ethernet connection 156, thesecond PoE signal receiver 165 can respond by providing a sufficientresistance with respect to the voltage V_(P2) to indicate to the PSEdevice 152 that the PD 154 is coupled via the Ethernet connection 156.Therefore, the PSE device 152 can determine the resistance value of thePoE signal receivers 164 and 165 based on a ΔI/ΔV of the separateamplitudes V_(VALID1) and V_(VALID2). At a time T₃, the voltage V_(P2)decreases back to the amplitude V_(MIN), thus concluding the detectionphase, based on which the PoE controller 160 identifies that both PORT 1and PORT 2 are coupled to the respective first and second PoE signalreceivers 164 and 165. While the detection phase is demonstrated in theexample of FIG. 5 as including only a single pulse of the voltagesV_(P1) and V_(P2) at the single amplitude V_(VALID), it is to beunderstood that the detection phase could include additional pulsesand/or additional amplitudes in the detection phase voltage amplituderange, such as dictated by the IEEE 802.3at standard, for each of thevoltages V_(P1) and V_(P2).

At the time T₄, the PSE device 152 switches to a classification phase,during which the PoE controller 160 can determine whether the PD 154 hasa capacity for PoE control, can determine a nominal power level of thePD 154, and can provide a power setting command to the PoE signalreceiver(s) 164 and 165. Beginning at the time T₄, the PSE device 152provides a first event classification to the first PoE signal receiver164, demonstrated at 102 as a 2-Event classification. Thus, at. the timeT₄, the voltage V_(P1) increases to an amplitude V_(CLASS) in a firstclass event. The amplitude V_(CLASS) can correspond to a voltageamplitude in a classification amplitude range amplitude (e.g., betweenapproximately 15.5 volts and approximately 20.5 volts). In response tothe Increase of the voltage V_(P1) of the first class event in the firstevent classification 202, the PoE signal receiver 164 can provide afirst class value (e.g., Class 4). At a time T₅, the voltage V_(P1) candecrease to an amplitude V_(MRK), corresponding to a mark event. As anexample, the mark event can signify to the first PoE signal receiver 164the end of the first class event of the event classification 202.Similarly, at a time T₆, the voltage V_(P1) increases to the amplitudeV_(CLASS) in a second class event of the event classification 202, inresponse to which the PoE signal receiver 64 can provide a second classvalue (e.g., Class 4), followed by another mark event at a time T₇. Asan example, the first and second initial class values can be equal(e.g., Class 4). Thus, the first PoE receiver 164 can respond to thefirst event classification with a class signature that comprises twoClass 4 current responses to the respective two class events of thefirst event classification 202. The example of FIG. 5 demonstrates thatthe first event classification 202 comprises two class events in a2-Event classification scheme, such as to ensure a linear response to asubstantially constant amplitude of the voltage signal V_(PORT) at theclassification amplitude range. However, it is to be understood that thePSE device 152 can be configured to provide the first eventclassification as a 1-Event classification by providing a single classevent, or based on providing more than two class events.

At a time T₈, the PSE device 152 provides a second event classificationvia PORT 2, demonstrated at 204, at which the voltage V_(P2) increasesto an amplitude V_(CLASS) in a class event at the time T₈. In responseto the class event of the second event classification 204, the secondPoE signal receiver 165 can provide a second class signature (e.g.,Class 5). At a time T₉, the voltage V_(P2) can decrease to the amplitudeV_(MRK), corresponding to a mark event, thus signifying to the secondPoE signal receiver 165 the end of the class event of the eventclassification 204. The second class signature can be provided by thesecond PoE signal receiver 165 at a value that is different from thefirst class signature, thus potentially signifying to the PoE controller160 that the PD 154 may have a capacity for PoE control.

At a time T₁₀, the PSE device 152 provides a third event classificationvia PORT 2, demonstrated at 206, at which the voltage V_(P2) increasesto the amplitude V_(CLASS) in a class event at the time T₁₀. In responseto the class event of the third event classification 206, the second PoEsignal receiver 166 can provide a third class signature that is lessthan the second class signature (e.g., Class 0-4). At a time T₁₁, thevoltage V_(P2) can decrease to the amplitude V_(MRK), corresponding to amark event, thus signifying to the second PoE signal receiver 165 theend of the class event of the third event classification 206. The thirdclass signature can be provided by the second PoE signal receiver 166 ata value that is less than the second class signature to indicate to thePoE controller 160 that the PD 154 has a capacity for PoE control. Inaddition, the specific class value of the third class signature 206 canindicate to the PoE controller 160 the nominal power level of the PD154, such as demonstrated previously in Table 1.

As described previously, in response to identifying the nominal powerlevel of the PD 154, the PoE controller 160 can be configured to controlthe power level of the PD 154 as a function of the nominal power level,such that the power output of the PD 154 can be variably controlled bythe PoE controller 160. At a time T₁₁, the PoE controller 160 can beginto provide a number of class events via one or both of the voltagesV_(P1) and V_(P2) associated with a code corresponding to the powersetting command. As an example, the power setting command can be encodedbased on a quantity of pulses of the class events corresponding to apredetermined percentage of the nominal power level, such as providedpreviously in Table 2. As an example, the additional class events thatindicate the percentage of nominal power level can be provided solelyvia the voltage V_(P1), solely via the voltage V_(P2), or based on acombination of the voltages V_(P1) and V_(P2). For example, the code canbe based on a sum of the quantity of class events provided via thevoltages V_(P1) and V_(P2), or the code can be based on a binary and/ortime-based encoding of the class events provided via the voltages V_(P1)and V_(P2). Thus, the additional class events that indicate thepercentage of nominal power level can be provided to any of a variety ofways.

In response to the code, the first and/or second PoE signal receivers164 and 165 can identify the percentage of the nominal power level thatis desired to be output from the PD 154 by the PoE controller 160. As aresult, at a time T₁₃, the PSE device 152 begins operating in theactivation phase, and thus provides the voltage signal V_(PORT) at amaximum amplitude to provide the voltages V_(P1) and/or V_(P2) at theamplitude V_(PORT) _(_) _(PSE). Therefore, the PD 154 can operate at thepercentage of the nominal power level based on the power commandsetting. Accordingly, the PoE control system 150 described herein canoperate to provide PHY layer power control of the PD 154 in a simplisticand variable manner over multiple ports via the Ethernet connection 156.

In view of the foregoing structural and functional features describedabove, a method in accordance with various aspects of the presentinvention will be better appreciated with reference to FIG. 6. While,for purposes of simplicity of explanation, the method of FIG. 6 is shownand described as executing serially, it is to be understood andappreciated that the present invention is not limited by the illustratedorder, as some aspects could, in accordance with the present invention,occur in different orders and/or concurrently with other aspects fromthat shown and described herein. Moreover, not all illustrated featuresmay be required to implement a method in accordance with an aspect oftire present Invention.

FIG. 6 illustrates an example of a method 250 for providing powercontrol in a PoE control system. At 252, event classifications (e.g.,event classifications 102,104, and 106) of a voltage signal (e.g., thevoltage signal V_(PORT)) are provided via an Ethernet connection (e.g.,the Ethernet connection 16) from a PSE device (e.g., the PSE device 12).At 254, a nominal power level is indicated based on a class signature(e.g., the class signature 106) via a PoE signal receiver (e.g., the PoEsignal receiver 20) of a powered device (e.g., the PD 14) based on aclass current of the voltage signal. At 256, a power setting commandassociated with a quantity of class events of the voltage signal (e.g.,at the time T₁₁ in the example of FIG. 3) is provided from the PSEdevice to the PoE signal receiver. The power setting command cancorrespond to a percentage of the nominal power level (e.g., Table 1).At 258, the PD is activated to operate at the percentage of the nominalpower level based on the power setting command.

What have been described above are examples of the invention. It is, ofcourse, not possible to describe every conceivable combination ofcomponents or method for purposes of describing the invention, but oneof ordinary skill In the art will recognize that many furthercombinations and permutations of the invention are possible.Accordingly, the invention is intended to embrace all such alterations,modifications, and variations that fall within the scope of thisapplication, including the appended claims.

What is claimed is:
 1. A power-over-Ethernet (PoE) control systemcomprising: a powered device (PD) that is configured to receive avoltage signal via an Ethernet connection and which comprises a PoEsignal receiver configured to indicate a nominal power level via thereceived voltage signal; and a power sourcing equipment (PSE) deviceconfigured to generate the voltage signal and to measure a class currentof the voltage signal to determine the nominal power level, the PSEdevice comprising a PoE controller configured to provide a power settingcommand as a function of the nominal power level to the PoE signalreceiver via the voltage signal, such that the PD can operate at a powerlevel that is based on the power setting command.
 2. The system of claim1, wherein the PSE device is configured to provide the power settingcommand as a function of the nominal power level based on providing thevoltage signal as a quantity of class events associated with a codecorresponding to a desired percentage of the nominal power level.
 3. Thesystem of claim 1, wherein the PoE signal receiver is configured toindicate the nominal power level via a class signature corresponding toa magnitude of the class current associated with the voltage signal,wherein the PSE device is configured to provide the power settingcommand subsequent to the PoE signal receiver indicating the nominalpower level.
 4. The system of claim 3, wherein the class signature has aclass value corresponding to one of a plurality of predetermined nominalpower levels.
 5. The system of claim 1, wherein the PoE signal receiveris configured to provide a first class signature of the class current inresponse to a first event classification associated with the voltagesignal, and a second class signature in response to a second eventclassification, the second class signature having a different classvalue from the first class signature, and a third class signature inresponse to a third event classification, with the third class signaturebeing different from the second class signature to indicate that the PDhas a capacity for PoE control by the PSE device.
 6. The system of claim5, wherein the third class signature has a class value that correspondsto one of a plurality of nominal power levels, such that the third classsignature indicates the nominal power level of the PD to the PSE device.7. The system of claim 5, wherein the first class signature Is providedfrom the PD at Class 4, wherein the second class signature is providedfrom the PD at Class 5, and wherein the third class signature isprovided from the PD at a class level corresponding to the nominal powerlevel.
 8. The system of claim 1, wherein the PD comprises a first PoEsignal receiver and a second PoE signal receiver, and wherein the PSEdevice is configured to provide a first voltage signal to the first PoEsignal receiver and a second voltage signal to the second PoE signalreceiver, wherein the first PoE signal receiver is configured to providea first class signature of the class current in response to a firstevent classification of the first voltage signal and wherein the secondPoE signal receiver is configured to provide a second class signature inresponse to a second event classification associated with the secondvoltage signal, wherein the second class signature has a greater classvalue from the first class signature to indicate that the PD has acapacity for PoE control by the PSE device.
 9. The system of claim 8,wherein the second PoE signal receiver is configured to provide a thirdclass signature in response to a third event classification associatedwith the second voltage signal, wherein the third class signature has adifferent class value from the second class signature and wherein thethird class signature is less than the second class signature toindicate that the PD has a capacity for PoE control by the PSE device,wherein the third class signature corresponds to the nominal power levelto the PSE device.
 10. The system of claim 9, wherein the PSE device isconfigured to provide the power setting command as a function of thenominal power level based on providing at least one of the first andsecond voltage signals as a quantity of class events corresponding to adesired percentage of the nominal power level subsequent to theindication of the nominal power level via the third class signature. 11.A PoE lighting system comprising the PoE control system of claim
 1. 12.A method for providing power control in a power-over-Ethernet (PoE)control system, the method comprising; providing event classificationsof a voltage signal via an Ethernet connection from a power sourcingequipment (PSE) device; indicating a nominal power level based on aclass signature via a PoE signal receiver of a powered device (PD) basedon a class current of the voltage signal; providing a power settingcommand associated with a quantity of class events of the voltage signalfrom the PSE device to the PoE signal receiver, the power settingcommand corresponding to a percentage of the nominal power level; andactivating the PD to operate at the percentage of the nominal powerlevel based on the power setting command.
 13. The method of claim 12,further comprising indicating a capacity for PoE control by the PSEdevice based on a plurality of class signatures, wherein indicating thenominal power level comprises indicating the nominal power level basedon a last of the plurality of class signatures.
 14. The method of claim13, wherein providing the event classifications comprises providing afirst event classification, a second event classification, and a thirdevent classification, wherein indicating the capacity for PoE controlcomprises indicating the capacity for PoE control by the PSE devicebased on a first of the plurality of class signatures provided inresponse to the first event classification and a second of the pluralityof class signatures provided in response to the second eventclassification, wherein the first and second of the plurality of classsignatures have different class values, and based on a third of theplurality of class signatures that has a class value that is less thanthe second of the plurality of class signatures.
 15. The method of claim12, wherein indicating the nominal power level comprises indicating thenominal power level based on a value of the last of the plurality ofclass signatures corresponding to one of a plurality of predeterminednominal power levels, wherein providing the power setting commandcomprises providing the power setting command corresponding to apercentage of the one of the plurality of predetermined nominal powerlevels.
 16. The method of claim 12, wherein providing the eventclassifications comprises providing a first event classification via afirst port of the Ethernet connection and providing a second eventclassification via a second port of the Ethernet connection, whereinindicating the nominal power level comprises indicating the nominalpower level based on a first class signature via a first PoE signalreceiver of the PD based on a class current of a first voltage signaland a second class signature via a second PoE signal receiver of the PDbased on a class current of a second voltage signal, and whereinproviding the power setting command comprises providing the powersetting command associated with a quantity of class events of at leastone of the first voltage signal and the second voltage signal to arespective at least one of the first PoE signal receiver and a secondPoE signal receiver.
 17. A power-over-Ethernet (PoE) control systemcomprising: a powered device (PD) that is configured to receive avoltage signal via an Ethernet connection and which comprises a PoEsignal receiver configured to provide a first class signature inresponse to a first event classification via a class current of thereceived voltage signal and a second class signature via the classcurrent, the second class signature having a different class value fromthe first class signature, and a third class signature that has a classvalue that is less than the second class signature to indicate that thePD has a capacity for PoE control, the third class signature indicatinga nominal power level of the PD; and a power sourcing equipment (PSE)device configured to generate the voltage signal and to measure theclass current of the voltage signal to determine the capacity for PoEcontrol and the nominal power level, the PSE device comprising a PoEcontroller configured to provide a power setting command as a functionof the nominal power level to the PoE signal receiver via the voltagesignal, such that the PD can operate at a power level that is based onthe power setting command.
 18. The system of claim 17, wherein the PSEdevice is configured to provide the power setting command as a functionof the nominal power level based on providing the voltage signal as aquantity of class events associated with a code corresponding to adesired percentage of the nominal power level.
 19. The system of claim17, wherein the PD comprises a first PoE signal receiver and a secondPoE signal receiver, and wherein the PSE device is configured to providea first voltage signal to the first PoE signal receiver and a secondvoltage signal to the second PoE signal receiver, wherein the first PoEsignal receiver is configured to provide a first class signature of theclass current in response to a first event classification of the firstvoltage signal and wherein the second PoE signal receiver is configuredto provide a second class signature in response to a second eventclassification associated with the second voltage signal, wherein thesecond class signature is configured to indicate that the PD has acapacity for PoE control by the PSE device based on being greater thanthe first class signature.
 20. The system of claim 18, wherein thesecond PoE signal receiver is configured to indicate the nominal powerlevel via the third class signature corresponding to the nominal powerlevel to the PSE device, and wherein the PSE device is configured toprovide the power setting command as a function of the nominal powerlevel based on providing at least one of the first and second voltagesignals as a quantity of class events associated with class signaturescorresponding to a desired percentage of the nominal power level.